Add &prefix:<|> to flatten arrays into positional arguments.

src/NQP/Actions.pm

@@ -494,6 +494,15 @@ method arglist($/) {
         }
         else { $past.push($expr); }
     }
+    my $i := 0;
+    my $n := +$past.list;
+    while $i < $n {
+        if $past[$i].name eq '&prefix:<|>' {
+            $past[$i] := $past[$i][0];
+            $past[$i].flat(1);
+        }
+        $i++;
+    }
     make $past;
 }
 

src/NQP/Grammar.pm

@@ -417,6 +417,7 @@ token prefix:sym<~>   { <sym>  <O('%symbolic_unary, :pirop<set S*>')> }
 token prefix:sym<->   { <sym>  <![>]> <O('%symbolic_unary, :pirop<neg>')> }
 token prefix:sym<?>   { <sym>  <O('%symbolic_unary, :pirop<istrue>')> }
 token prefix:sym<!>   { <sym>  <O('%symbolic_unary, :pirop<isfalse>')> }
+token prefix:sym<|>   { <sym>  <O('%symbolic_unary')> }
 
 token infix:sym<*>    { <sym>  <O('%multiplicative, :pirop<mul>')> }
 token infix:sym</>    { <sym>  <O('%multiplicative, :pirop<div>')> }

t/nqp/41-flat.t

@@ -0,0 +1,15 @@
+#!./parrot nqp.pbc
+
+# flattened arguments
+
+plan(3);
+
+sub xyz($x, $y, $z) {
+    ok( $x == 7, 'first argument');
+    ok( $y == 8, 'second argument');
+    ok( $z == 9, 'third argument');
+}
+
+my @a := [7,8,9];
+xyz(|@a);
+